Solenoid-operated diaphragm valves for use in irrigation systems are known to the art. Valves of this general type are described, for example, in U.S. Pat. No. 3,336,843 and in U.S. Pat. No. 3,410,301. This type of valve includes a diaphragm which moves against or away from an annular seat within the valve to open or close the valve. The diaphragm is normally biased against the seat by a spring and by the fluid pressure in the chamber above the diaphragm acting against the diaphragm. When the valve is to be opened, the fluid pressure in the diaphragm chamber is relieved by causing the fluid to pass out of the diaphragm chamber by a solenoid controlled pilot valve. An improved and simplified construction for such a valve is disclosed in U.S. Pat. No. 4,505,450 which is assigned to the present Assignee.
However, the valve shown in U.S. Pat. No. 4,505,450 does not includes any means for throttling the flow of fluid through the valve when the valve is opened. The present invention is directed to such a valve as disclosed in the patent and which includes a simple adjustable mechanism for controlling the fluid flow through the valve when the valve is opened.